Chronic effects of oral prostacyclin analogue on thromboxane A and prostacyclin metabolites in pulmonary hypertension

Abnormal biosynthesis of thromboxane and prostacyclin has been implicated in patients with primary pulmonary hypertension and secondary pulmonary hypertension associated with congenital heart disease, and could be involved in the pathogenesis of pulmonary vascular disease. The chronic effects of an oral prostacyclin analogue, beraprost sodium, on thromboxane and prostacyclin biosynthesis and on pulmonary circulation were investigated in 15 children with pulmonary hypertension. The plasma concentrations of thromboxane B, and 6-keto-prostaglandin F1_α were measured, as was the urinary excretion of 11-dehydro-thromboxane B, and 2.3-dinor-6-keto-prostaglandin F1_α, which are stable metabolites of thromboxane A, and prostacyclin, respectively. In patients with pulmonary hypertension, the plasma concentration of thromboxane B. and the ratio of thromboxane B, to 6-keto-prostaglandin F1_α were greater than in healthy controls: 210 ± 49 versus 28 ± 4 pg/mL (P<6.05) and 32.6 ± 8.9 versus 5.7± 1.8 (p<0.01), respectively. After 3 months of administration of beraprost. the plasma concentration of thromboxane B, and the ratio of thromboxane B, to 6-keto-prostaglandin F were reduced significantly: 210 ± 49 to 98 ± 26 pg/mL (P < 0.01) and 32.6 ± 8.9 to 18.0 ± 6.7 (P < 0.05). respectively. In contrast, the plasma concentrations of 6-keto-prostaglandin F in patients were slightly but not significantly higher than in controls, and did not change significantly after administration of beraprost. The concentrations of 11-dehydro-thromboxane B, and 2.3-dinor-6-keto-prostaglandin F, in urine correlated significantly with thromboxane B, and 6-keto-prostaglandin F. respectively, in plasma. Beraprost improved the imbalance of thromboxane and prostacyclin biosynthesis and has a potential efficacy for preventing the progressive development of pathological changes in pulmonary vasculature.